In manufacturing of semiconductors, various chemical agents are used. Such chemical agents are dealt with in a state of being stored in a liquid tank. In semiconductor manufacturing factories equipped with semiconductor manufacturing equipment, the liquid tank is used with a liquid tank connector attached thereto for delivering liquid in the liquid tank to the outside.
FIG. 7 shows a prior art liquid tank with a liquid tank connector attached thereto, such as shown in FIG. 16 of Japanese Unexamined Patent Application Publication No. 2002-114242. The liquid tank 70 is formed with two plugged ports 71, 71a. The respective plugged ports 71, 71a are fixed with a liquid flow channel connecting plug 72 and a gas flow channel connecting plug 72a, respectively. A siphon tube 73 which extends to a position in the vicinity of the bottom of the liquid tank 70 is connected to the liquid flow channel connecting plug 72.
Caps (not shown) are attachable to the respective plugs 72, 72a, and the liquid tank 70 is adapted to be transported or stored in a state in which hole portions are closed by the caps.
When taking (delivering) liquid in the interior out from the liquid tank having the configuration as described above, the caps are removed from the respective plugs 72, 72a first, and then sockets 75, 75a attached to distal ends of hoses 74, 74a are connected to the plugs 72, 72a, respectively. Then, by activating a pump P provided at the liquid flow channel hose 74, the liquid in the liquid tank 70 is delivered from the siphon tube 73. At this time, since the pressure in the tank assumes a negative pressure by reduction of the liquid in the liquid tank 70, an inert gas is supplied into the liquid tank 70 via the gas flow channel hose 74a to compensate the pressure reduction.
PCT International Publication No. WO 2005/119115 describes, a liquid tank connector which is able to deliver liquid and supply inert gas only with one plugged port provided on the liquid tank is disclosed. In other words, the liquid tank connector is adapted to form a liquid flow channel for delivering the liquid in the liquid tank and a gas flow channel for supplying the inert gas into the liquid tank in a state in which one plug and one socket are connected.